Capitalization: change a few mentions of calibre to lowercase

The author likes it that way. See http://calibre-ebook.com/about

frontend/ui/widget/opdsbrowser.lua

@@ -35,7 +35,7 @@ local CatalogCache = Cache:new{
 
 local OPDSBrowser = Menu:extend{
     opds_servers = {},
-    calibre_name = _("Local Calibre catalog"),
+    calibre_name = _("Local calibre catalog"),
 
     catalog_type = "application/atom%+xml",
     search_type = "application/opensearchdescription%+xml",

plugins/calibrecompanion.koplugin/main.lua

@@ -114,9 +114,9 @@ function CalibreCompanion:initCalibreMQ(host, port)
         self.calibre_socket:start()
         self.calibre_messagequeue = UIManager:insertZMQ(self.calibre_socket)
     end
-    DEBUG("connected to Calibre", host, port)
+    DEBUG("connected to calibre", host, port)
     UIManager:show(InfoMessage:new{
-        text = _("Connected to Calibre server at ") .. host .. ":" .. port,
+        text = _("Connected to calibre server at ") .. host .. ":" .. port,
         timeout = 1,
     })
 end
@@ -147,14 +147,14 @@ function CalibreCompanion:connect()
     else
         DEBUG("cannot connect to calibre")
         UIManager:show(InfoMessage:new{
-            text = _("Cannot connect to Calibre."),
+            text = _("Cannot connect to calibre."),
         })
         return
     end
 end
 
 function CalibreCompanion:disconnect()
-    DEBUG("disconnect from Calibre")
+    DEBUG("disconnect from calibre")
     self.calibre_socket:stop()
     UIManager:removeZMQ(self.calibre_messagequeue)
     self.calibre_socket = nil